1. Field of the Invention
This invention relates to new liquid or fluid polyamine/carbonic acid salt compositions free from crystalline content and their preparation from mixtures containing at least one aliphatic or cycloaliphatic polyamine, an aliphatic or cycloaliphatic hydroxyamine having at least one hydroxyl group and at least one amino group, and water, and optionally diluents and/or conventional auxiliary agents and additives, by mixing the aforesaid components with carbon dioxide. The invention further relates to the use of these liquid polyamine/carbonic acid salt compositions for the preparation of polyurethane ureas which are optionally foamed, especially for the coating of substrates or production of sheet products, using isocyanate prepolymers in which the isocyanate groups are preferably blocked and the liquid polyamine/carbonic acid salt compositions as chain lengthening agents and/or crosslinked agents and at the same time as physiologically harmless blowing agents.
2. Description of the Prior Art
It is known to produce carbonates or bicarbonates of amines from the said amines or polyamines, carbon dioxide and water. The products obtained are generally fairly high melting, crystalline compounds which are insoluble or difficultly soluble in the hydroxyl compounds conventionally used for the preparation of polyurethanes. These crystalline carbonic acid salts of the amines, such as, for example, bicarbonates and/or carbonates, optionally with different degrees of hydration, may be reacted with compounds containing isocyanate groups or compounds capable of reacting like isocyanate groups to produce relatively high molecular weight compounds containing urea groups. Thus, U.S. Pat. No. 3,425,964 teaches the hardening of polyurethane resins with solid aminecarbonates which have unlimited stability at 25.degree. C. The said U.S. patent specification also teaches the production of foamed products from the said compounds. JP-A No. 50,052,175 discloses the preparation of molded polyurethane products from a polyurethane reaction mixture with the addition of a (cyclo)-aliphatic diaminecarbonate such as, for example, 1,6-diaminohexanecarbonate at temperatures below the decomposition temperature of the carbonate. To harden the product and fix the form, it is heated above the decomposition point of the amino carbonate.
DBP No. 838,217 describes the preparation of linear polyureas by thermal condensation of diisocyanates and carbonic acid salts of diamines. JP-A No. 7,213,068 teaches the use of amine carbonates for the production of polyurethane foam heat sealing compounds.
In the present state of the art, amine/CO.sub.2 adducts (carbamates or carbonates) are only known to be used in the form of crystalline products. These crystalline CO.sub.2 adducts must be used in a very finely divided form in order to avoid uneven hardening. In addition, it is necessary to take precautions to prevent the deposition of such dispersed amine/CO.sub.2 adducts. Furthermore, it is well known to the man of the art that the cross-linking of compounds containing isocyanate groups with solid substances present in a heterogeneous phase can only be achieved with considerable effort and frequently leads to inferior products since the said solid substances cannot be sufficiently firmly linked and chemically incorporated. The need to use the diamine/CO.sub.2 adducts in the form of very finely divided suspensions for their reaction with the polyisocyanates even applies to reactions of crystalline CO.sub.2 adducts in highly polar solvents such as dimethylformamide (see DE-B No. 1,223,154).
In French Pat. No. 1,413,484 it has also been disclosed to prepare polyhydrazodicarboxylic acid amides or polyureas containing alcoholic hydroxyl groups in highly polar solvents such as dimethylformamide or dimethylacetamide by reacting solutions of the carbonic acid salts of the diamines containing alcoholic hydroxyl groups, such as N-hydroxyethylhexane-1,6-diamine or 1,3-diamino-propanol-2 with aromatic diisocyanates in solvents at -20.degree. C. to +30.degree. C. In this reaction, the carbonic acid salts are dissolved or suspended in highly polar solvents and are formed in the highly polar solvents, optionally with the addition of hydroxydiamines and optionally also diamines or hydrazines not containing hydroxyl groups. If, however, diamines without hydroxyl groups (e.g., ethylene diamine) are added, insoluble, crystalline amine salts separate. Reaction of the amine salts with the polyisocyanates forms solutions from which hard, homogeneous polyureas are obtained by evaporation of solvent.
It was, therefore, an object of the present invention to avoid the disadvantages known in the art of using crystalline aminecarbonates as chain lengthening agents and enable amine carbonate reactions to be carried out without highly polar solvents. It was also an object of the present invention to provide non-crystalline compositions containing carbonates and/or bicarbonates of aliphatic and/or cycloaliphatic primary or secondary polyamines, preferably primary diamines. It was also an object of the invention to provide high proportions of cycloaliphatic primary diamines in liquid form as an amine/carbonic acid salt mixture. It was yet a further object of the present invention to provide a process for the preparation of foamed sheet products from polyurethane ureas, using physiologically harmless products as blowing agents. The invention also seeks to provide an easily workable liquid non-crystalline mixture which will act both as chain lengthening agent or cross-linking agent and as blowing agent donor in the formation of polyurethanes, the carbon dioxide functioning as inert, physiologically harmless blowing agent.
It has now surprisingly been found that carbonic acid salts (carbonates and/or bicarbonates) of mixtures of
(1) aliphatic and/or cycloaliphatic polyamines, preferably diamines having primary and/or secondary amino groups and PA1 (2) hydroxyamines to be defined in more detail below, preferably (poly)amines containing hydroxyalkyl groups, optionally in the presence of additional quantities of water and optionally certain solvents as diluents do not crystallize but exist in a liquid or pasty fluid state. PA1 (1) aliphatic or cycloaliphatic polyamines having primary and/or secondary amino groups (preferably primary amino groups), preferably polyamines having 2 to 4 amino groups, most preferably primary diamines, especially cycloaliphatic diamines, and PA1 (2) aliphatic or cycloaliphatic hydroxypolyamines having at least one hydroxyl group and at least one amino group (preferably mono- to tris-hydroxyalkylpolyamines, most preferably mono- and bis-hydroxyalkyl-alkylene diamines), PA1 (3) optionally diluents in the form of organic solvents having a boiling point below about 160.degree. C. and being at least partially soluble in water, in quantities of up to about 90% by weight of diluent (preferably up to about 60% by weight, most preferably up to about 30% by weight) in the total mixture of (1) to (6), PA1 (4) optionally further known auxiliary agents and additives, PA1 (5) from about 0.01 mol to 5 mol (preferably from about 0.1 to 1.0 mol, most preferably from about 0.15 to 0.7 mol) of water per amine equivalent, but at least 1 mol of water per mol of carbon dioxide, and PA1 (6) about 0.01 to 0.99 mol of CO.sub.2 per amine equivalent (preferably from about 0.05 to 0.80 mol, most preferably from about 0.1 to 0.5 mol). PA1 (1) aliphatic or cycloaliphatic polyamines containing primary and/or secondary amino groups (preferably primary amino groups), preferably polyamines having from 2 to 4 amino groups, most preferably primary diamines, especially primary cycloaliphatic diamines, and PA1 (2) aliphatic or cycloaliphatic hydroxypolyamines having at least one hydroxyl group and at least one amino group (preferably mono- to tris-hydroxyalkylpolyamines, most preferably mono- and di-hydroxyalkyl-alkylene diamines) in proportions of (1):(2) of from about 95:5 to 10:90% by weight (preferably from about 80:20 to 25:75% by weight, most preferably from about 65:35 to 30:70% by weight) optionally in the presence of PA1 (3) diluents in the form of organic solvents which have a boiling point below about 160.degree. C. (preferably below about 146.degree. C.) and are at least partially soluble in water, in quantities of up to about 90% by weight of diluent (preferably from about 0 to 60% by weight, most preferably from about 0 to 30% by weight), in the total mixture of (1) to (6), optionally adding PA1 (4) further known auxiliary agents and additives PA1 (5) water, the quantity of water being from about 0.01 to 5 mol (preferably from about 0.1 to 1.0 mol, most preferably from about 0.15 to 0.7 mol) of water per amine equivalent and at least 1 mol of water per mol of carbon dioxide, and PA1 (6) sufficient carbon dioxide so that the quantity of incorporated CO.sub.2 per amine equivalent is from about 0.01 to 0.99 mol of CO.sub.2 (preferably from about 0.05 to 0.80 mol, most preferably from about 0.1 to 0.5 mol). PA1 (A) isocyanate prepolymers containing an average of 2 to 4 optionally blocked aromatic and/or aliphatic and/or cycloaliphatic isocyanate groups, having an isocyanate content of from about 1 to 24% by weight (preferably from about 1.7 to 6% by weight), PA1 (B) chain lengthening agents and/or cross-linking agents, and optionally PA1 (C) known auxiliary agents and additives and solvents, characterized in that component (B) comprises at least 50 equivalent percent (preferably at least 75%), most preferably 100% of the non-crystalline, liquid or fluid polyamine/carbonic acid salt compositions according to the invention with up to 50 equivalent percent, if desired, of conventional chain lengthening agents or cross-linking agents.
These carbonic acid salt mixtures are characterized by the absence of crystalline components. It has also surprisingly been found that solvents which are normally non-solvents for bicarbonates or carbonates may be added to the adduct mixtures before, during or after formation of the mixed carbonic acid salts according to the invention to lower the viscosity without causing precipitation of the carbonic acid salt components. Preferably, only a portion of the amino groups in the mixture is converted into carbonic acid salts with carbon dioxide.